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February 15-17th Storm Threat


OHweather

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The models shifting east has me concerned. I went all rain and mentioned flooding here given 1-2" of QPF and snow melting and running off on frozen ground, but the 4km drills us and is usually one of the farther NW models. I'd look like a complete a** if we get anything more than 2" :lol:

 

I'm trying to figure out why the 4KM NAM is 50 miles further west than the 12KM NAM? Any thoughts?

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I'm trying to figure out why the 4KM NAM is 50 miles further west than the 12KM NAM? Any thoughts?

It's a slightly different model. It uses the 12km for initialization and for its boundary conditions IIRC but is higher res and can explicitly show convection instead of paramaterizing it. That's the main difference I can think of but they're somewhat different models
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0z GFS isn't as weenie-tastic as the 4km NAM here, but its warm layer only gets as warm as 1C to briefly 2C here and isn't deep. I don't think I pull off anything too exciting here but that's very close, and I quietly put a snow mention back into my school's forecast for Monday night

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ILN:

 

THERE IS UNCERTAINTY IN TIMING THIS TRANSITION AND
IF IT HAPPENS EARLIER THAN FORECAST THEN PARTS OF CENTRAL OHIO
COULD GET SUBSTANTIAL ACCUMULATIONS. BUT FOR NOW HAVE KEPT
ACCUMULATIONS IN THAT AREA AROUND AN INCH.

 

 

so 1-substantial is their call.

 

Biggest zone of potential surprise is probably from the far eastern suburbs of CMH to Zanesville.   Newark guys right in there.

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ILN:

 

THERE IS UNCERTAINTY IN TIMING THIS TRANSITION AND

IF IT HAPPENS EARLIER THAN FORECAST THEN PARTS OF CENTRAL OHIO

COULD GET SUBSTANTIAL ACCUMULATIONS. BUT FOR NOW HAVE KEPT

ACCUMULATIONS IN THAT AREA AROUND AN INCH.

 

 

so 1-substantial is their call.

 

Biggest zone of potential surprise is probably from the far eastern suburbs of CMH to Zanesville.   Newark guys right in there.

 

Well, here is ILN's worst (or best?) case scenario. Looks like you're in the game too buckeye.

post-1196-0-94444000-1455541256_thumb.jp

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Updated models for TO(QPF)

6z RGEM: 0.6-0.8"

0z ECMWF: 0.35"

0z EPS: 0.45"

6z HRDPS: 0.8-1.2"

6z GFS: 0.1-0.2"

6z NAM/WRF: 0.1-0.2"

What an easy forecast...

 

3z SREF mean is at 0.70"...so that gives some credibility to the GEM based models. But I remember how poorly they performed during last weeks meandering low and I feel like we'll get burned if we buy into those solutions.

 

The experimental HRRR (which goes to 24 hours), which another hi res model, seems to support the westerly models....

 

totp_t7sfc_f24.png

 

It's tough...I'm going to withhold making a first call until after the 12z runs come in.

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3z SREF mean is at 0.70"...so that gives some credibility to the GEM based models. But I remember how poorly they performed during last weeks meandering low and I feel like we'll get burned if we buy into those solutions.

The experimental HRRR (which goes to 24 hours), which another hi res model, seems to support the westerly models....

totp_t7sfc_f24.png

It's tough...I'm going to withhold making a first call until after the 12z runs come in.

The 0z UKIE is also in the west camp. This is as tough as it gets but my gut tells me the west camp wins or it's a blend of the Euro/EPS and the RGEM suite. Would like some of the other mesos to join the RGEM to give it more credibility.
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The 0z UKIE is also in the west camp. This is as tough as it gets but my gut tells me the west camp wins or it's a blend of the Euro/EPS and the RGEM suite. Would like some of the other mesos to join the RGEM to give it more credibility.

 

Yeah, I was hoping the 4km NAM would have been in that camp. It may be a touch west of the OP NAM but not a huge difference.

 

Such a tough (and exciting I gotta say) forecast. 30-40 miles difference in where this thing track could mean the difference between 1" or 10" for us. :lol:

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Newstalk 1010 saying 2cm possible. Anything substantial and Torontonians will be surprised, especially considering our largest snowfall is 3.5" so far.

I wonder if EC pulls the trigger on watches/warnings if the RGEM/HRDPS remain bullish.

 

That's basically EC's forecast. They've only gone 2-4cm for the Niagara peninsula while Niagara County NY is under a WSW :lol: So they've outright rejected the RGEM/HRGEM, and even the EURO it seems. Looks like they're riding the further east camp. I have to say, climo would seem to support the NAM/GFS eastern solution, and with all the uncertainty I don't blame them for being uber conservative.

 

I think a SWS encompassing the GTA and Hamilton/Niagara would have been helpful...just in case the wetter models turn out to be correct. If the 12z runs come in favourably their hand might be forced.

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Although a much different setup, I'm getting a flashback to Dec. 11, 2014. I believe the HRDPS was the first model to sniff out high QPF values (around 0.7-0.8") for that storm. And it was on the money.

 

9z SREF mean QPF for YYZ plummets to 0.36" from 0.69" at 3z. Not picking out any trends just bouncing back and forth.

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That's basically EC's forecast. They've only gone 2-4cm for the Niagara peninsula while Niagara County NY is under a WSW :lol: So they've outright rejected the RGEM/HRGEM, and even the EURO it seems. Looks like they're riding the further east camp. I have to say, climo would seem to support the NAM/GFS eastern solution, and with all the uncertainty I don't blame them for being uber conservative.

 

I think a SWS encompassing the GTA and Hamilton/Niagara would have been helpful...just in case the wetter models turn out to be correct. If the 12z runs come in favourably their hand might be forced.

 

Totally agree with the bolded. Regarding niagara, even the direst models have 4-6". Anything lower is a bit silly.

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Too bad the mid levels of this system don't develop more. The sfc track is a dream for us but without a closed H7/H5 low it doesn't really develop an expansive deformation zone well to the W/NW of the sfc storm. Instead we have this narrow corridor of snow which we have to sweat each model run.

 

that's what makes this a real kick in the nuts, of course you guys just have to sweat the precip location, we have to sweat precip location AND temp issues.   

 

you guys are threading a needle.... we are threading a needle with mittens on

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Too bad the mid levels of this system don't develop more. The sfc track is a dream for us but without a closed H7/H5 low it doesn't really develop an expansive deformation zone well to the W/NW of the sfc storm. Instead we have this narrow corridor of snow which we have to sweat each model run.

I'm holding out hope.

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Too bad the mid levels of this system don't develop more. The sfc track is a dream for us but without a closed H7/H5 low it doesn't really develop an expansive deformation zone well to the W/NW of the sfc storm. Instead we have this narrow corridor of snow which we have to sweat each model run.

 

 I find the models do a poor job of picking up snow deformation bands on the fringes of lows, which are often the places where deformation bands set up. I recall a winter or two ago where it looked like a very sharp snow accumulation gradient between downtown Toronto and the 401, with the 401 getting next to nothing... 401 ended up getting the most due to deformation band on the dringe.

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I find the models do a poor job of picking up snow deformation bands on the fringes of lows, which are often the places where deformation bands set up. I recall a winter or two ago where it looked like a very sharp snow accumulation gradient between downtown Toronto and the 401, with the 401 getting next to nothing... 401 ended up getting the most due to deformation band on the dringe.

Feb 5, 2014. North York got around a foot I think. Downtown got 8-9".

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that's what makes this a real kick in the nuts, of course you guys just have to sweat the precip location, we have to sweat precip location AND temp issues.   

 

you guys are threading a needle.... we are threading a needle with mittens on

 

Yeah, Apps runners are rare breads. You think once we get one everything could just go perfectly. :lol:

 

post-257-0-26355200-1455546424_thumb.jpg

 

12z NAM doesn't seem to think thermals will be a problem for OH. But CMH riding the razor's edge like we are.

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 I find the models do a poor job of picking up snow deformation bands on the fringes of lows, which are often the places where deformation bands set up. I recall a winter or two ago where it looked like a very sharp snow accumulation gradient between downtown Toronto and the 401, with the 401 getting next to nothing... 401 ended up getting the most due to deformation band on the dringe.

 

If some mid level frontogenetic forcing develops we'll be in the likely spot that it does.

 

Just one more small push to the west and I'll be happy. 1-2' would be nice but I'll settle for 8".

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